The disclosure relates to an antenna adjustment circuit, an antenna adjustment method, and a communication unit, in which a resonance frequency of an antenna is adjusted.
In recent years, there has been often used a communication technique called near-field communication (NFC). The near-field communication is a non-contact communication of which communication range is around tens of centimeters. An example of such a communication technique in Japan includes FeliCa (registered trademark). A communication function of the near-field communication is often provided such as in an IC card and a portable telephone, which may be held over a piece of equipment to thereby perform such as authentication in passing through a ticket gate of transportation including trains and in entering a building. The applicability of the near-field communication has been further expanded nowadays through the use of such near-field communication for electronic money, for example.
Such an IC card, a portable telephone (a communication unit), or the like that has the function of the near-field communication includes therein such as an antenna and a circuit for transmitting and receiving data through the antenna. As for such antenna, circuit, and the like, various studies have been made, as disclosed in Japanese Patent Registration Nos. 3874145, 4379446, and 4609394, for example.